1. Field of the Invention
The present invention relates to a sublimation thermal transfer image receiving material and an image recording method therefor, and more particularly, to a card type sublimation thermal transfer image receiving material having good recording properties and good image qualities and durability of a recorded image, as well as to an image recording method which cost-efficiently produces a good image on such a card type sublimation thermal transfer image receiving material.
2. Discussion of the Related Art
Recently, the demand for full color recording has increased year by year. There have been known various full color recording methods including electrophotographic recording methods, ink jet recording methods and sublimation thermal transfer recording methods. Among these methods, sublimation thermal transfer recording methods are widely employed because of having the following advantages over the other recording methods:
(1) a full color image having excellent image qualities can be obtained; PA0 (2) recording speed is relatively high; and PA0 (3) operation and maintenance of the recording apparatus are relatively easy. PA0 (1) a card merely made of a resin plate such as polyvinyl chloride, polyester, acrylonitrile-butadiene-styrene copolymer (ABS) or the like and having a print image thereon; PA0 (2) a card having a resin plate and a magnetic stripe which is formed on the resin plate and in which a small amount of information such as a personal identification number is stored; and PA0 (3) a card having a resin plate and an IC chip which is mounted on or in the resin plate and which can store a relatively large amount of information compared to the magnetic stripe. PA0 (1) a resin cover film which is recessed corresponding to the projection of an antenna coil, an IC chip, a condenser and the like which are formed on a resin film substrate is overlaid on the resin film substrate (resin cover film overlaying method); and PA0 (2) a resin cover film is formed on a resin film substrate having an antenna coil, an IC chip, a condenser and the like by an injection molding method (resin cover film injection molding method). PA0 (1) a circuit and an antenna are printed with silver paste on resin film substrate such as polyester film or the like having thickness of from about 20 to about 500 .mu.m, and preferably from about 100 to about 250 .mu.m, and then an IC chip, a condenser and the like are mounted on the film substrate with an adhesive agent to form a main functional part on the film substrate(the circuit and the antenna may be previously formed and mounted on the resin film substrate with an adhesive agent); and PA0 (2) a resin cover film is formed on the resin film substrate having the main functional part by "an injection and compression molding method" so that the total thickness of the IC card is in the above-mentioned range. PA0 (1) a melted resin material is injected under low pressure into a cavity of a die which contains a resin film substrate having a main functional part and which is slightly opened or loosely fastened so as to contain an excessive amount of the injected resin material, the die is then closed to compress the melted resin material in the cavity after or during the injection of the melted resin material, and then the die is cooled while compressing the injected resin material to solidify the resin material so that there is no camber or shrink marks on the surface of the formed resin cover film; and PA0 (2) a melted resin material is injected into a cavity of a die which contains a resin film substrate having a main functional part and which is fastened, and the injected resin material is cooled while at least one part of the injected resin material is pressed by a cylinder which acts on the inside of the die to exert pressure on the injected resin material to smooth the surface of the resultant resin cover film. PA0 (1) a resin including hollow particles is coated on the IC card and dried to form a porous intermediate layer; PA0 (2) a resin including a foaming agent is coated on the IC card, dried and heated to form air bubbles in the resin layer, resulting in formation of a porous intermediate layer; PA0 (3) a resin dissolved in solvents including a solvent which hardly dissolves the resin is coated on the IC card and dried to form a porous intermediate layer; and PA0 (4) a porous resin film including hollow particles or air bubbles therein is adhered to the IC card to form a porous intermediate layer. PA0 (1) a porous resin film in which a foaming agent included in a resin film is foamed to obtain a porous resin film; and PA0 (2) a porous resin film such as synthetic paper in which a resin film including an additive is drawn biaxially or uniaxially to form air bubbles therein. PA0 (1) a resin film which includes an ultraviolet absorbing agent and on which, if desired, a layer of metal is formed by evaporation is superimposed on the image recorded receiving material and adhered with an adhesive agent which is thermosensitive or pressure sensitive; PA0 (2) a transferable protective layer including an ultraviolet absorbing agent which is formed on a heat resistant substrate and which, if desired, has a thermosensitive or pressure sensitive adhesive layer thereon is transferred onto the image recorded receiving material by heating the back side of the substrate; PA0 (3) a transferable protective layer including an ultraviolet absorbing agent which is formed on a temporary substrate with a releasing layer therebetween is transferred onto the image recorded receiving layer; or PA0 (4) a transferable protective layer including an ultraviolet absorbing agent which is repeatedly formed on an area adjacent to each of ink layers which are repeatedly formed in a recording material is transferred onto the image recorded receiving layer by heating the back side, i.e., a heat resistant layer side, of the recording material after the image is recorded on the receiving layer using the ink layer of the recording material. PA0 C.I. Disperse Yellows 1, 3, 8, 9, 16, 41, 54, 60, 77 and 116; PA0 C.I. Disperse Reds 1, 4, 6, 11, 15, 17, 55, 59, 60, 73 and 83; PA0 C.I. Disperse Blues 3, 14, 19, 26, 56, 60, 64, 72, 99 and 108; PA0 C.I. Solvent Yellows 77 and 116; PA0 C.I. Solvent Reds 23, 25 and 27; and PA0 C.I. Solvent Blues 36, 63, 83 and 105. PA0 (1) a recording method in which an image is formed on a receiving material using a one-time recording method but the recording material is repeatedly used n-times (referred to as an n-time mode multiple recording method); and PA0 (2) a recording method in which an image is formed on a receiving material while the recording material is fed at a speed of 1/n that of the receiving material (referred to as an n-fold speed mode multiple recording method). PA0 (1) the recording material and the receiving material perfectly adhere to each other by the heat for recording images, resulting in occurrence of transfer of the ink layer to the receiving material; or PA0 (2) the recording material and the receiving material adhere to each other for a moment, resulting in occurrence of an undesirable horizontal white line in a recorded image. PA0 (1) both of a dye supplying layer coating liquid and a dye transferring layer coating liquid are coated on a respective sheet made of the same substrate and dried to form two sheets of single-ink-layer type recording materials so that each coating weight of the dye supplying layer and the dye transferring layer is the same; PA0 (2) each of the prepared recording materials is superimposed on a respective sheet of the same receiving materials so that the coated surface of each recording material contacts the receiving layer of the receiving material, and heat is applied from the back side of each recording material, namely, heat is applied from the side of the substrate opposed to the ink layer, to record an image on the receiving layer; and PA0 (3) the image density of each recorded image is measured, and the recording material having the higher image density has higher dye transferability. PA0 (1) the dye concentration in the dye supplying layer is higher than that in the dye transferring layer; and/or PA0 (2) the diffusion coefficient of the dye supplying layer is greater than that of the dye transferring layer. PA0 (1) preparing a coating liquid by mixing a resin solution having a solid content of 5 to 20% by weight and a silicone oil which is a mixture of SF8417 and SF8411 (both of which are manufactured by Toray Silicone Industries Inc.) mixed in a ratio of 1/1 so that the ratio of the silicone oil to the solid of the resin is 0.3; PA0 (2) coating the coating liquid on a sheet of synthetic paper, Yupo FPG#95 manufactured by Oji Yuka Synthetic Paper Co., Ltd., and drying the coated liquid for 1 minute to form a receiving layer so that the thickness of the receiving layer is 10 .mu.m on a dry basis; PA0 (3) aging the thus obtained receiving material at room temperature for more than 1 day; PA0 (4) superimposing a cyan colored recording material, e.g., Ck2LB used for Mitsubishi Color Video Copy Processor, on the receiving layer of the receiving material and recording an image on the receiving layer by imagewise heating the back side of the recording material using a thermal printhead, e.g., KMT-85-6MPD4 (manufactured by Kyocera Corp.), having a dot density of 6dots/mm and an average electric resistance of 542 .OMEGA., under a condition of applied energy of 2.00 mJ/dot; and PA0 (5) measuring the image density of the recorded image with a Macbeth reflection densitometer RD-918. PA0 (1) measuring the coating weight of the receiving layer when the receiving layer is formed; PA0 (2) cutting a sheet of the receiving material 50 mm wide and 100 mm long, and measuring the weight of the sheet; PA0 (3) dipping the sheet into 500 g of the methyl ethyl ketone (or a good solvent for the binder resin in the receiving layer) for ten minutes; PA0 (4) pulling up the sheet from the methyl ethyl ketone and measuring the weight of the sheet after drying the solvent included in the sheet; and PA0 (5) obtaining the degree of gelation by the following equation: (degree of gelation)={1 -(weight difference between the sheet before dipping and after dipping)/(coating weight of the receiving layer of 50 mm wide and 100 mm long)} .times.100 (%). PA0 (1) forming a semiconductive layer on a substrate which includes a heat resistant resin such as, polyester, polycarbonate, triacetyl cellulose, nylon, polyimide and aromatic polyamide, and powder of a metal such as, aluminum, copper, iron, tin, nickel, molybdenum and silver which is dispersed in the heat resistant resin, and forming an ink layer including a sublimable dye on the semiconductive layer; or PA0 (2) forming a semiconductive layer including powder of the above-mentioned metal described in method (1) on a substrate by an evaporation or a sputtering method and forming an ink layer including a sublimable dye on the semiconductive layer.
In sublimation thermal transfer recording, an image can be obtained on a sublimation thermal transfer image receiving material (referred to as a receiving material) upon application of heat to the back side of a sublimation thermal transfer image recording material (referred to as a recording material) whose ink layer contacts the receiving material. The recording material includes a substrate and an ink layer which is formed on the substrate and includes a thermo-diffusional dye (hereinafter referred to as a sublimable dye) dispersed in a binder resin. The recording material may include a heat resistant layer on the back side thereof. The receiving material includes a substrate and optionally an image receiving layer (referred to as a receiving layer) which is formed on the substrate. When heat is applied to the recording material, the sublimable dye diffuses into the receiving material or the receiving layer of the receiving material, so that an image is formed on the receiving material.
Currently, various cards such as credit cards, cash cards, identification cards, cards bearing personal medical data, membership cards or the like are widely used.
Cards are roughly classified as follows:
The card having an IC chip (referred to as an IC card) is predicted to be widely used in the future.
Types of IC card include a noncontact-reading type IC card in which an antenna, an IC chip, a coil and the like are mounted in a card, and a contact-reading type IC card in which an IC chip and a coil are mounted on a card and terminals are exposed on the surface of the card.
Currently, there is a tendency to mount a portrait of an owner on these cards to prevent other persons from using the cards. A suitable method for mounting a portrait on a card is a sublimation thermal transfer recording method in which an image can be directly recorded on a card material having a relatively low softening point such as polyvinyl chloride by imagewise heating a recording material, whose ink layer is contacting the surface of the card, using a thermal printhead. The sublimation thermal transfer recording method is widely employed for this application because of having the above-mentioned advantages, and particularly, being a dry image forming process and easily producing an image having excellent image qualities as good as those of a photograph using silver halide. Card materials for the card type receiving material have also been studied in which a receiving layer which can be easily dyed with a sublimable dye is formed on the entire surface or an area of a resin card material which is safer in environmental pollution than polyvinyl chloride.
Methods for making a noncontact-reading type IC card include the following methods:
An IC card manufactured by the resin cover film overlaying method is expensive because it takes much expense in time to manufacture the IC card. In contrast, an IC card manufactured by the resin cover film injection molding method is not expensive; however, the resultant IC card has a drawback in that the surface of the formed resin cover film is relatively roughened compared to the surface of the IC card manufactured by the resin cover film overlaying method because the IC card manufactured by the injection molding method tends to have camber and/or shrink marks compared to cards having a magnetic stripe which are manufactured by a blanking method.
When an image is recorded on a card having such a rough surface by a sublimation thermal transfer recording method, the recorded image has defects such as white spots, white lines or unevenness of image density. This is because an image cannot be recorded or is unevenly recorded on a recess of the rough surface of the resin cover film. In attempting to solve this problem, when a card is made by an improved injection molding method in which the cooling time after the injection of the resin cover film is prolonged, the resultant card has a smooth surface; however the card is expensive because it takes much expense in time to manufacture the card.
Because of these reasons, a need exists for a noncontact-reading type IC card receiving material on which images having good image qualities can be cost-efficiently recorded by a sublimation thermal transfer recording method.